The present invention relates to internal combustion engine pistons which may be adapted to motor vehicles.
In an internal combustion engine, a piston is subject to high combustion pressure, and thereby subject to a side force because of inclination of a connecting rod with respect to the piston. The side force presses the piston on a cylinder wall, and causes a large frictional force between a thrust-side skirt of the piston and the cylinder wall. Accordingly, internal combustion engine pistons are designed to bear such side forces, and reduce such frictional forces. On the other hand, there is demand for weight reduction of internal combustion engine pistons.
Japanese Patent Application Publication No. 2008-190357 discloses an internal combustion engine piston which includes a thrust-side skirt, an anti-thrust-side skirt, and a pair of aprons between the thrust-side skirt and the anti-thrust-side skirt, where each connecting section between one of the skirts and one of the aprons is formed with a stress dispersing portion for dispersing a stress that is concentrated in the connecting section due to difference in thermal expansion and elastic deformation between the skirt and the apron.